My Code review

以下是原代码：

import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {
    private Button btn;
    private ImageView imageView;
    private ProgressDialog progressDialog;
    private final String IMAGE_PATH = "http://www.baidu.com/img/bd_logo1.png";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button) findViewById(R.id.btn);
        imageView = (ImageView) findViewById(R.id.imageView);
        progressDialog = new ProgressDialog(MainActivity.this);
        progressDialog.setTitle("提示信息");
        progressDialog.setCancelable(false);
        progressDialog.setMessage("正在下载，请稍候。。。");
//        progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new MyAsyncTask().execute(IMAGE_PATH);
            }
        });

    }

    public class MyAsyncTask extends AsyncTask<String, Integer, byte[]> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            progressDialog.show();
        }

        @Override
        protected byte[] doInBackground(String... strings) {
            byte[] image = new byte[] {};
            HttpURLConnection conn = null;
            InputStream inputStream = null;
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

            try {
                URL url = new URL(strings[0]);
                conn = (HttpURLConnection)url.openConnection();
                if (conn.getResponseCode() == 200) {
                    long file_length = conn.getContentLength();
                    long total_length = 0;
                    int length = 0;
                    byte[] data = new byte[1024];
                    inputStream = conn.getInputStream();
                    while (-1 != (length = inputStream.read(data))) {
                        total_length += length;
                        byteArrayOutputStream.write(data, 0, length);
                        int progress = ((int) (total_length*100/(float)file_length));
                        publishProgress(progress);

                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    image = byteArrayOutputStream.toByteArray();
                    inputStream.close();
                    byteArrayOutputStream.close();
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }finally {
                conn.disconnect();
            }
            return image;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            super.onProgressUpdate(values);
            progressDialog.setProgress(values[0]);
        }

        @Override
        protected void onPostExecute(byte[] bytes) {
            super.onPostExecute(bytes);
            Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
            imageView.setImageBitmap(bitmap);
            progressDialog.dismiss();
        }
    }
}

代码审查结果：

　　1、缺少注释

　　2、对非常规行为和边界值情况处理没有描述

　　3、存在部分重复的代码